<!Doctype html>
<html>
<head>
<meta charset="utf-8">
<title ></title>
<script>
function myFunction(){
setInterval(function(){alert("快来注册吧")},3000);
}
function initial(){
setInterval("changeLogo()",1000);
}
var i=0;
function changeLogo(){
i++;
document.getElementById("logo1").src="logo"+i+".jpg";
if(i==3){
i=0;
}
}
</script>
<style>
.header{
height:60px;
border:1px solid red;
}
 .top ul li{
float:left;
width:33.2%;
}
ul{
list-style:none;
}
.center{
height=300px;
}
</style>
</head>
<body onload="initial()">

<div>
<div class="header">

<div class="top">

<ul>
<li><a href="#" onclick="myFunction()">注册</a></li>
<li><a href="#">登录</a></li>
<li><a href="#">购物车</a></li>
</ul>
</div>
</div>

<div class=center>
<div >
<img src="logo1.jpg" width="100%" id="logo1"/>

</div>
</div>


</div>
</body>
</html>